Hook for forming steel tubing



t, 2 1 f' 1643008. Sep o 927 J. Fl-:NTREss y HOOKFOR FORMING STEEL TUBING N4/'1 n Filed June22, 1922 2 Sheets-Sheet 1 5 sept. zo, 1921. 1,643,008

- J. FENJREss HOOK FOR FORMING STEEL TUBING Filed June 22. 1922 .2, sheets-sheet Particular attention is called to the .iactI that in Figure 1, the central axis of the iinished tube (10) is not parallel to the path ot travel of the metal strip 12, as it goes through the guiding blocks or former (16) adjacent. to the profile wheels (13); but is at any desired angle with reference to each other, the length and curvature ot the track (18) simply conforming thereto. The hook plate (20) is made by taking a flat bar or sheet ot' steel ot suiiicient size to be attachable to the support in the manner described, forming through it a perforation (2(3) whose .inside diameter corresponds to the outside diameter' oit that portion of strip 12 which bears on the inside o1 said perl'oration; slitting the front portion oil the plate adjacent to the bottom of the perto 1ation (26u) to 'form the slot 3 bend ing the lip portion (29) et the plate below the slot (28) to one side, viz: toward the track (18) in the assembled structure oli the drawing, so as to :torni a tube bending cani surface extending from (c) to in Figure (5; shaping the next 180U (32) ot the cireuiniterence oi perforation (26a) and represented by the distance (f) to (g) in F igure G, so that it is a cani which properly bends and 'forms the inet-al strip to the linal pitch el the linished tube (10) and finally bending the lip portion (33, Figure 7) of the plate innncdiately above the slot (2S) so that the portion et the hook or die (34) from (g) to (7L) (Figure (5) has less pitch than portion (32) from to (g) (Figures G and S), the same having the functions hereafter described. The port-ion e to f is also a traekway leading to the main cam, f-g, and portion g-7b is also a trackway leading from the main cam.

As indicated in the above paragraph, cam surit'are (30') nierelytakes metal strip (12) as it comes from track (18) and bends it in general in conformity with the curvature of track (1S) until the metal strip reaches cani portion (32) which is so shaped and de signed that it imparts the final spiral to the linished tube (l0) and delivers it to cam portion which is, as shown in F igure at a less pronounced pitch than the cani (32), so that the tube (10) 'formed and pitched by the cam member is forced to take a less pitch as it is guided back along earn (34) from (g) to (li) (Fig ure 6). The eltect is, as shown in Figures 1, 2 and to give a ready clearance space between adjacent interiitting parts of the metal strip, so that the rubber packing 14 can be fed into place with ample clearance space (36) (Figure 1) while the rubber is going into place. As soon as the finished tube (10) passes out et' the control of cani portion (311), the natural spring in the metal strip (12) causes it to return to the position defined by the cam portion (32) with the result that the linal tube is produced, as shown in the right hand halt ol? Figure fl, `with the rubber packing (141;) l'irmly gripped between it'our compressing tlanges oil. the metal strip. In other words, the cani surface (32) puts such a decided pitch in the metal strip (12) that it would, it leitt to itself, travel in the path designated in dotted line (-10) olf Figure 8, but .it is `toi-ced because oit the necessity ot the presence of the rubber packing (lil) to lie in the position indicated by the' dotted lines (4l-2) of Figure S.

i1s `the product ot the mechanism is a. metal cylinder olf tube strip 12 emerging at right angles from plate 2t), it is highly dcsii-able, il? not necessary, that all pointsl on the interior circumterential surface c to /L of the perforation through the plate include the pa .'allel surface lines ot an imaginary (.fvlinder, co-axial with tube cylinder 12, passing through the plate at said pertoration.

ln .Figure t5, the angle (a) shows the pitch ot cam angle (b) shows the pitch ol rain i'ace (ill) and angle (c) shown the curvature oli cani Ytace (30) which is approximately that otl track Particular attention is called to the vtact that cam plate or hook (20) only engages and con trois one-half of the metal strip (12), the theoryT being that the tool `or hook by actually controlling and crimping this halt' oli the metal strip eilcctually controis the whole ot the cross Section ol: the strip. Owing to the fact ot control oit the tube by engaging only one-halt or less ot the metal strip, the die not nearly as expensive to make as `would be one which entirely surrounded all parts ol the metal strip;` the power to push the metal strip through the die is not nearly as great as would be required to push. the complete metal strip through a die which completely enclosed it. `ln actual practice, the hook o i this invention reduces the power required to .torni a metal tube anproxinuilely 50% and reduces the cost olI the hook or die about 8th/1i; when compared to a die conu'iletely enclosingl the ribbon on its convex surface.

.t is entirely possible. in theoryl at least` to construct a hook el2 this invention which will completely control and mold the strip 12 troni the position shown in the le'ift hand halt o't F igures l. and 2 to the finished tube position; but, in actual practice, it is lar better to use a curved track for partiallv bending or crimping the strip, and to only use the device ot this invention 'for giving the finishing definite linal touch to theinetal strip as it goes into the linal tube.

The hook described is novel in that it is the iirst device oit the kind .in which the `tube is forined by pushing or pulling it through or around the hook with or without the aid luc of a live or dead mandrel in the center of the tube to support the tubein formation; or tv assist in propelling the tube through the hook or both. The hook is novel in that it governs only one half ofthe strip, or less thanl half, in coiling same into tubing. The hook as shown governs the left half of the strip as in Figure l, but a similar hook governing the right half of strip would give the result desired. It is almost impossibley to accumulatev galvanization or dirt in this hook, etc. This results in many advantages in the practical production of tubing which it seems unnecessary to set forth in detail. hat I claim is: l. A hook for laterally bending metal tubing strip of suitable cross section to form a f proper tube, the same comprising an initially fiat plate of suitable thickness to lie between `the walls of one half of the section of the strip, there being through the plate a perforation for finished tubing, and a slit in the plate outward from one point in said perforation so that a tube strip may kpass C' through said slit into and around the perforation and thence out of the slit as described, the plate being laterally bent adjacent to the slit and about the perforation for4 the purposes setforth. f

2. A hook for laterally bending metal tubing strip of S-shaped cross section to form a proper tube, the same comprising an initially flat plate of suitable thickness to lie between the walls of one U-shaped half of the S' sectionV of the strip, therev being through the plate a perforation for nished tubing, and a slit in the plate outward from one point in said perforation so that a tube strip may pass through said slit into and one point insa-id perforation so that a tube strip may pass through said slit into and around the perforation and thence out of the slit as described, the plate being laterally bent adacent to the slit and about the perforation, the interior circumference of the perforation including at all points in the laterally bentk plate lines lying'parallel to each other and in the circumference of an imaginary cylinder passed through the plate at. said forth.

4. A hook for laterally bending S-shaped tubing strip to form it into a tube, the same comprising an initially flat plate of suitable thickness to lie in one U-shaped space on not more than half of the tubing strip, the same being perforated to receive the tube-and then slitted outward at one point in the perforation, for the purposes set .perforation to the edge of the plate, the lip portions, adacent to said slit, being bent laterally in opposite directions to form tracks on which tubing may enter and leave the slit, the middle portion of the plate adjacentto the circumference of said perforation being inclined to laterally bend or, pitch tubing strip led into and out of said perg foration via said tracks and forced to travel around the interior of saidperforation.

5. A die or hook for laterally bending metal strip into helical form comprising a relatively thin metal plate, having cut in it cam track adapted to engage not more than half of the metal tube strip to be formed and provided with guiding means by which such a metal strip may be forced over said cam track surface to laterally bend the entire strip.

6. In a device of the class described, a com,-

paratively thin plate perforated near'its middle and bent laterally adjacent to said perforationto form a cam track for laterally. bending strip passed around the circumference of said perforation, and trackways leading to said main cam track opening out to opposite sides of the plate for the purposes set forth.

7. In a device of the class described, a comparatively thin plate perforated near its middle and bent laterally adjacent to' said perforation to form a cam track for laterally bending strip passed around the circumV ference ofV saidperforation, and trackways leading to said main cam track opening out to opposite sides of the plate, one of said last mentioned ltrackways being also a cam of less angularity than the main cam forthe purposes set forth. Y

8. A hook for laterally bending metal tubing strip of suitable cross-section to form a proper tube, the same comprising an initially flat plate of no greater width than the distance between the walls of one half of the section of the strip and cooperating means formed out of said plate itself.

In witness whereof, VI have hereunto subscribed my name.

JAMES FENTRESS. 

